Spatiotemporal change in growth of two populations of Asian chum salmon in relation to intraspecific interaction

Abstract

Spatiotemporal changes in growth patterns of chum salmon Oncorhynchus keta that returned to the Ishikari (Japan) and Namdae (Korea) rivers in 1984-1998 were investigated using scale analysis. Juvenile chum salmon from both populations left coastal marine areas after spring at a size of over 8 cm fork length (FL). In summer, juvenile salmon from the Namdae River entered the Okhotsk Sea at a larger FL than Ishikari River juveniles. There were no significant differences in annual growth between populations of one-, two-, and four-year-old fish. For three-year-old fish, however, Namdae River salmon had significantly higher synchronous and sympatric growth than Ishikari River salmon.Mean FL of adults was also larger in Namdae River salmon than in Ishikari River salmon. ANCOVA results showed (1) negative linear relations between FL and catch, (2) homogeneous slopes of those relations at regional and species levels, and (3) non-homogeneous slopes at the population level, indicating that density dependent effects on growth were most significant at this level. We concluded that growth of chum salmon was concurrently influenced by stronger effects of intrapopulation competition and weaker effects of inter-and intra-specific interactions in the Bering Sea.

Dynamics of body size, age, and annual growth rate of Anadyr chum salmon Oncorhynchus keta in 1962–2010

“…3,4). Our data on speeding up the growth rate during the first year of life, together with similar results obtained by other researchers (Ishida et al, 993;Temnykh, 1999;Isakov et al, 2000;Kaev, 2003;Kaeriyama et al, 2007;Ruggerone et al, 2007Ruggerone et al, , 2009Martinson et al, 2008;Seo et al, 2009), evi dence to favorable conditions for chum salmon growth after the migration of juveniles to the sea during the last decades. In addition, our analysis performed sep arately for the first and the second areas of the annual zone of chum salmon scale growth confirmed the presence of favorable conditions for both periods, i.e., summer-autumn growth period (post catadromous juvenile, the first part of the annual zone) and autumn-winter period (the second part of the annual zone) (Figs.…”

“…These parame ters reflect the combined effect of numerous internal and external limiting factors, and they may be used as an integral productive characteristic. Studies of multi year dynamics of the body size of Pacific salmon spe cies of Oncorhynchus genus evidence to the significant differences in body size and weight for the specimens that are back to spawn (Efanov and Chupakhin, 1982;Ishida et al, 1993;Welch and Morris, 1994;Bigler et al, 1996;Kaeriyama, 1998Kaeriyama, , 2003Volobuev V. and Volobuev M., 2000;Temnykh et al, 2002;Kaev, 2003;Sviridov et al, 2004;Helle et al, 2007;Mathinsen et al, 2007;Zavolokin et al, 2008;Seo et al, 2009;Temnykh, 2009). Chum salmon O. keta attracts spe cial attention.…”

Long-term climate-related changes in somatic growth and population dynamics of Hokkaido chum salmon

“…We used samples from only the dominant age group, i.e., 4-year-old female salmon (Seo et al 2009). We did not use male salmon, because male adults exhibit too much variability in body size within a population due to secondary sexual characters (Salo 1991).…”

“…We did not use male salmon, because male adults exhibit too much variability in body size within a population due to secondary sexual characters (Salo 1991). We analyzed time series of scale and fork lengths (FLs) from O. keta released from hatcheries and recaptured as adults on their return to the Ishikari River on the west coast of Hokkaido Island, Japan, in 1943(Kaeriyama et al 2007Seo et al 2009). A total of 2,936 scales were measured from the focus to each annual ring (i.e., r 1 , r 2 , r 3 , R), and the data were used to estimate increases in FL from the beginning to the end of each year (i.e., L 1 , L 2 , L 3 , L 4 ) according to the back-calculation method ( Fig.…”

“…A total of 2,936 scales were measured from the focus to each annual ring (i.e., r 1 , r 2 , r 3 , R), and the data were used to estimate increases in FL from the beginning to the end of each year (i.e., L 1 , L 2 , L 3 , L 4 ) according to the back-calculation method ( Fig. 1; modified from Seo et al 2009). R and r i indicate the total scale radius and scale radius at age i, respectively.…”